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adf9ae0d15
In commit9f0b4807a4("um: rework userspace stubs to not hard-code stub location") I changed stub_segv_handler() to do a calculation with a pointer to a stack variable to find the data page that we're using for the stack and the rest of the data. This same commit was meant to do it as well for stub_clone_handler(), but the change inadvertently went into commit84b2789d61("um: separate child and parent errors in clone stub") instead. This was reported to not be compiled correctly by gcc 5, causing the code to crash here. I'm not sure why, perhaps it's UB because the var isn't initialized? In any case, this trick always seemed bad, so just create a new inline function that does the calculation in assembly. Reported-by: subashab@codeaurora.org Fixes:9f0b4807a4("um: rework userspace stubs to not hard-code stub location") Fixes:84b2789d61("um: separate child and parent errors in clone stub") Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at>
47 lines
1.1 KiB
C
47 lines
1.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
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* Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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*/
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#include <signal.h>
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#include <sched.h>
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#include <asm/unistd.h>
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#include <sys/time.h>
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#include <as-layout.h>
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#include <ptrace_user.h>
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#include <stub-data.h>
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#include <sysdep/stub.h>
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/*
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* This is in a separate file because it needs to be compiled with any
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* extraneous gcc flags (-pg, -fprofile-arcs, -ftest-coverage) disabled
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*
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* Use UM_KERN_PAGE_SIZE instead of PAGE_SIZE because that calls getpagesize
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* on some systems.
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*/
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void __attribute__ ((__section__ (".__syscall_stub")))
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stub_clone_handler(void)
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{
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struct stub_data *data = get_stub_page();
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long err;
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err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
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(unsigned long)data + UM_KERN_PAGE_SIZE / 2);
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if (err) {
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data->parent_err = err;
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goto done;
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}
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err = stub_syscall4(__NR_ptrace, PTRACE_TRACEME, 0, 0, 0);
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if (err) {
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data->child_err = err;
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goto done;
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}
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remap_stack_and_trap();
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done:
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trap_myself();
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}
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